U study: man’s face evolved to take a hit

N-mans Face Courtney Tanner
(Credit: Reconstruction by John Gurche; photographed by Tim Evanson)

(Credit: Reconstruction by John Gurche; photographed by Tim Evanson)

Cavemen may not have gotten into bar fights, but they did learn how to take a few punches.

A recent study published in “Biological Reviews” by David Carrier, a biology professor at the U, and Michael Morgan, a resident of the Emergency Medicine Department of the U’s Medical School, suggests violence played a part in the evolution of the shape men’s faces. Carrier and Morgan propose that man’s face has evolved to withstand punches.

The study does not assert that facial structure in humans is solely due to punching, but it challenges the currently held belief that the first apes to walk on two legs developed their unique facial characteristics to process hard food.

To support their claim, Carrier and Morgan drew on modern medical data about injuries to different areas of the body and bone structure differences between males and females in early apes and humans. The authors also cited other studies to show that fists were a common weapon in fights and that the face was the most commonly injured part of the body.

Carrier said the ability to form a fist was developing around the same time early man started to roam the earth on two feet, around four to five million years ago.

He says the correlation between punching and facial shape depended on the development of the “anatomy to allow them to throw a punch.” The study theorizes that being able to stand on two feet allowed early humans to strike more forcefully. As blows became more powerful, bones had to thicken to endure. This explains the thickened bones beneath man’s eyes and not just the bones around the jaw.

Differences between male and female facial bone structure in both early humans and modern humans show males generally have greater “protective buttressing” as the study calls it. The researchers argue that this indicates involvement in an activity likely to cause facial differences that males engaged in more frequently than females, such as fighting over a mate.

Morgan speaks from experience when he says facial injuries from a fight are common, even today. He works as an emergency physician and is a two-time black belt recipient. Hand injuries, by comparison, are much less common, providing some evidence of the effectiveness of the fist as a weapon, he said.

Modern man does not have nearly the pronounced facial robustness that early species did. The study presents the possibility that upper body strength in man decreased, leading to less need for protective muscles and bones in the skull.

Carrier and Morgan’s study has generated a lot of controversy, but they seem to be OK with that.

“We feel obligated as researchers to generate debate,” Morgan said.

Carrier said much of the attention given to the study is due to the topic and not necessarily the magnitude of the research. In fact, he feels media attention has no bearing on the importance of research because the study has yet to receive a published expert response.

Carrier and Morgan see a lot of potential in future musculoskeletal evolution research. They have been working on sets of data to improve their hypothesis on fist formation and produce a new hypothesis on the foot posture of ancient apes, which could potentially lead to more insights on our violent past.

k.tao@chronicle.utah.edu

@TaoKevin